Creating hole with square mortice

[okeydokey]

Thanks for all of the replies. This is for carraige bolts into Far Eastern plywood. They have to be removable and insertable many times.

I am now thinking that all I need to do is crush the bolt into the wood the first time to make the square hole after drilling a 5mm hole like @gcusick suggested.

I was reading that after doing this I could remove the bolt and use a thin epoxy resin to harden the impression but some sites I read said that it doesn't really work. Any thoughts on that?

Thanks!

Just a thought - will the nuts on the bolts be very tight? as if they will be made tight then the crushed/or other made square hole on tightening may become round and the square on the bolt shank will rotate in the hole and tightening become problematical.
A machine screw or a set screw or regular nut and bolt with a washer under the head (through a normal round hole) will tighten with spanner/socket/screwdriver many times.

 

[ChaiLatte]

"Here are the minimum and maximum shank diameters for coach bolts of different diameters:

Could the AI not find the M5 diameter which his hole will accommodate?

In addition, the concentricity of the square part of the coach bolt head with the cylindrical shank of the bolt is likely to vary considerably.

That creates challenges for the multiple remove and replace suggested above (post #14). Unless the same bolt is replaced in the same orientation in the same hole after the first insertion, problems are likely.

 

[Amplidyne]

Could the AI not find the M5 diameter which his hole will accommodate?

In addition, the concentricity of the square part of the coach bolt head with the cylindrical shank of the bolt is likely to vary considerably.

That creates challenges for the multiple remove and replace suggested above (post #14). Unless the same bolt is replaced in the same orientation in the same hole after the first insertion, problems are likely.

The AI couldn't be bothered. Suffice to say that it proves sufficiently that coach bolts aren't made to very close tolerances whatever the size.
Good point about the concentricity.

 

[MikeJhn]

Wouldn't a mortiser do this?

 

[Jake]

The AI couldn't be bothered. Suffice to say that it proves sufficiently that coach bolts aren't made to very close tolerances whatever the size.

Hmm, well it at least proves the AI 'thought' those were statistically most the likely answer to the words in the question. What refs did it provide?

 

[Nail]

T nuts instead?

Flip it round!